Polygonal building construction

ABSTRACT

A polygonal building having a perimeter wall made up of initially roughly plumbed rectangular wall sections in end-to-end but spaced-apart relation. Rafters extend from a common point approximately centrally of the building down to and between the upper ends of adjacent wall sections, and a perimeter cable is threaded through all of the wall sections and rafters. Tightening of the cable plumbs the wall sections, centers the rafters and thereafter prevents spreading of the roof and building when loads are imposed thereon.

United States Patent 1191 Walters 1 1 Sept. 30, 1975 [54] POLYGONAL BU DING CONSTRUCTION 3.335.535 8/1967 Lane 52 82 X 3.636.676 1 1972 [75] Inventor: Robert C. Walters, Tahoe City, 3807101 411974 3.827.200 8/1974 Preissler 52/82 1 Assigncc: Rondo Homes. Reno. FOREIGN PATENTS 0R APPLICATIONS 22 Fi 7, 1973 1.185.391 3/1970 United Kingdom 52/224 [2]] Appl No: 422852 Primary Examiner-Frank L. Abbott Assistant Examiner-Leslie A. Braun [52] U.S. Cl. 52/747'; 52/82; 52/227; y, g 1 0r i -Phi ip M re.

52/248 Weissenberger Lempio & Strabala [51] hit. Cl. E04G 21/14; E04B 1/35 '[58] Field of Search 52/82, 248, 247, 246, 227. [57] ABSTRACT A polygonal building having a perimeter wall made up of initially roughly plumbed rectangular wall sections [56] References cued in end-to-end but spaced-apart relation. Rafters ex- UNlTED STATES PATENTS tend from a common point approximately centrally of 2.256.050 9 1941 Hansen..- 52/246 x the building dOWH'IO and between the pp ends of 2.803.856 8/1957 Kofahl et a1 52/227 j nt ll sections, n a per m r ble is 3.118.186 1/1964 Moss... 52/82 X threaded through all of the wall sections. and rafters. 3.119.153 H1 arti 52/32 Tightening of the cable plumbs the. wall sections. cen- 33773520 10/1966 52/83 ters the rafters and thereafter prevents spreading of 3381999 I W966 f 2/127 x the roof and building when loads are imposed thereon. 3.295.265 1/1967 Hlta 52/247 X 3.333.373 8/ 1967 Taylor et al. 52/82 X 3 Claims, 8 Drawing Figures A I3 la l3 lOk lOd 1 10 J lob I3 US. Patent Sept. 30,1975 Sheet 2 of 3 3,908,329

POLYGONAL BUILDING CONSTRUCTION BACKGROUND OF THE INVENTION This invention relates generally to round buildings, i.e., buildings having a circular perimeter wall made up of a relatively large number of flat, rectangular wall sections in end-to-end relation, the wall sections being an equal distance from the center of the building. In particular the invention relates to such type buildings having a generally conical roof resting on the perimeter wall and wherein no horizontal trusses extend across the building to join the lower ends of the rafters together.

In such buildings the roof is supported vertically either primarily or completely by the perimeter wall. When loads are imposed on the roof, as by snow during winter, the roof rafters are urged to spread outwardly. Without reinforcing trusses, the spreading force imposed by the load acts outwardly on the perimeter wall upon which the roof rafters rest and to which the rafters are secured, and if the spreading force becomes too great the building will collapse. One method of increasing the wall strength is to put a band or cable around the perimeter of the wall, in much the same manner as a hoop is placed around a barrel. A disadvantage of this method is that the encircling cable will produce a hoop stress on the building, putting the wall sections in compression. This compressive force will vary throughout the year as roof loads vary.

The traditional method of erecting such buildings is to construct the perimeter wall, stud by stud, plumbing the walls for verticality as the wall is erected. After the wall has been completed and plumbed, the rafters are put in place and secured to the wall, usually by bolts. Prefabricated methods have been developed wherein wall sections and rafters are brought to the site for erection, the wall sections already having door and window framing therein and the rafters having been cut to length and having hard bolt holes drilled therethrough. Even through considerable savings in erection costs can be realized by using prefabricated parts, the wall sections must still be carefully plumbed as the perimeter wall is erected. This is particularly so because to obtain the benefit of using prefabricated rafters the bolt holes in the rafters must be in alignment with the bolt holes in the wall sections. If misalignment occurs the wall sections must be replumbed until the bolt holes come into registration. The plumbing of the walls and the subsequent bolting of the rafters to the walls are time-consuming operations which add to the cost of construction.

SUMMARY OF THE INVENTION The principal objects of the present invention are to provide a construction and method: wherein a perimeter cable is used to hold the rafters against spreading but in such a manner that the cable does not subject the wall sections to compressive forces; wherein the perimeter cable is itself used to secure the rafters to the wall sections; and, wherein final plumbing of the wall sections is done after the walls and rafters have been erected.

In general, the objects are accomplished by providing prefabricated wall sections each having a lengthwise passage through the upper end thereof and prefabricated rafters each having a horizontal passage through the lower end thereof. In erecting the building, the wall sections are installed and roughly plumbed. The rafters are installed roughly in place with the lower ends thereof being in the space between the upper ends of adjacent wall sections and with the rafter passages in general alignment with the wall section passages. As the rafters are installed a cable is threaded through the passages in the wall sections and rafter passages so that when all rafters have been installed the cable will extend completely around the perimeter of the buildings. The cable is then tightened, which causes the wall sections to be plumbed and centers the roof peak. The cable thereafter takes the roof load so that the wall sections are not subjected to a spreading force.

In addition, when constructed in accordance with the invention, the rafters are subjected only to compressive forces and no connections of the rafters to each other or to the perimeter wall are present which are subject to shear failure. The wall sections do not bear the weight of the roof and are not put under compression by the perimeter cable. Extending the perimeter cable through and within the wall sections is also advantageous in that the cable is hidden from sight so that it is protected from the elements and does not detract from the appearance of the building.

Other objects and advantages will become apparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, forming a part of this application and in which like parts are designated by like reference numerals throughout the same,

FIG. 1 is a sectional view, in elevation and through the center of a polygonal building being constructed in accordance with the present invention;

FIG. 2 is a view, as in FIG. 1, of the building after the wall sections and rafters have been plumbed and the rafter support posts have been installed;

FIG. 3 is a plan view of the building after the wall sections and rafters have been plumbed and some of the purlins and intermediate rafters have been attached;

FIG. 4 is an elevational view of the top part of a portion of the perimeter wall showing the manner in which the perimeter cable extends through the wall sections and rafters;

FIG. 5 is a sectional detail, taken on line 55 of FIG.

FIG. 6 is a plan view of the compression ring showin a rafter secured thereto;

FIG. 7 is a sectional view of the compression ring, taken on line 7-7 of FIG. 6;

FIG. 8 is a detail view in plan of a corner of the build- DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, wherein a preferred form of the invention is shown, the main structural components of the building are the wall sections 10a through 101, hip rafters ll, compression ring 12 and posts 13, all of which may be fabricated at a convenient location and brought to the site for erection. Although a twelve-sided building is shown, the building may have more or less sides, as desired.

Wall sections 10a through 101 are all rectangular and of the same overall width, length and height. As shown herein, the wall sections are of double wall construction with the exterior siding and interior wall applied to internal studding. The particular constructional design of a wall section will vary in accordance with the desires of the builder or architect involved, but typically a wall section a will have end studs 16 and 17, a top plate 18, a header 19 spaced below the top plate, a bottom plate 20 and spaced vertical studs 21. Wall section 10a includes framing for a window 22. Other wall sections will be framed for doors or windows or left as solid walls in accordance with the building design. Preferably the exterior siding 23 is installed on the wall sections before delivery to the site. The interior wall 24 is added later, during the final stages of construction.

The end studs 16 and 17 each have a hole 25 drilled therethrough, so that the holes 25 and the space between the top plate 18 and header 19 form a passage or raceway extending length-wise through the complete length of the wall sections at the upper end thereof.

For ease in illustration the other wall sections are shown in the drawings simply as solid members. However, it is to be understood that they will be constructed in essentially the same'way as wall section 10a, and, in particular, each will have a lengthwise passage completely through the upper end thereof.

The rafters 1 1 are precut to the proper length and the ends are shaped as desired. A horizontal cable passage 26 is drilled through the rafter at a predetermined distance from the upper end of the rafter, this distance being the same for all of the rafters 11.

The compression ring 12, as best seen in FIGS. 6 and 7, is polygonal in shape, having a lower flange 27 with downwardly and outwardly sloping faces 28, there being one face for each rafter of the building, the slope of the faces being equal to the desired pitch of the completed roof. Preferably a radially extending and upwardly projecting rib 29 is formed between each pair of faces 28 to help locate and center the rafters on the faces. Each face has fastener holes 30 formed therethrough. If the rafters are to be fastened by screws to the compression ring 12, pilot holes 31 are preferably drilled into the under side of the upper end of the rafters with a spacing corresponding to the fastener holes 30.

Compression ring 12 also has an upper flange 32 having a plurality of faces 33 which extend upwardly and outwardly and at right angles to faces 28. A web 34 extends across the interior of the compression ring.

After the prefabricated parts have been brought to the site, the wall sections are positioned in place on the subfloor 35. Depending on the particular construction involved, the bottom plates 20 of the wall sections will either have holes therein to fit onto upwardly extending ends of bolts embedded in floor 35 or else the bottom plate is nailed to the floor. The wall section is roughly plumbed, as by eye, and held in upright position by temporary braces 36 nailed to the wall sections and the floor, as shown in FIG. 1. It is desirable that the upper end of the wall section have some lateral play at this time. This play may be obtained from the inherent resiliency of the wall sections or else the wall sections may be relatively loosely bolted or nailed to the floor.

All of the wall sections are thus erected, in end-toend relation, to form the peripheral wall, with a space not less than the thickness of a rafter 11 being left between the ends adjacent wall sections.

The compression ring 12 is then mounted on the upper end of pole 37 which is put up and temporarily supported vertically at approximately the center of the building, the pole 37 being preferably of a length such' as to support the compression ring at its final desired height.

The rafters and perimeter cable are next installed, preferably as follows: A first rafter is hoisted into place and the upper end thereof is loosely fastened by screws to the compression ring. The lower end of the rafter is positioned between the ends of a pair of wall sections with the rafter passage 26 being in general registration with the holes 25 in the adjacent end studs of the wall sections. The lower end of the rafter is temporarily supported by a brace 38. The perimeter cable 40 has been delivered to the site in two lengths, and the end of one length is threaded through the rafter passage and end stud holes. The inclination of the temporary upright 38 can be easily adjusted to raise or lower the rafter and the upper ends of the wall sections can be moved easily towards or away from the center of the building so that the passages comeinto exact enough registration to enable the cable to be easily threaded therethrough.

The same operation is then carried out with the diametrically opposite rafter, the other cable length being used to pass through the adjacent studs and rafters. The remaining rafters are installed in place, working away from a previously installed rafter, with the two cable lengths being successively threaded through the rafters as they are installed.

When all of the rafters have been installed, the ends of the cable lengths are secured to the threaded eye bolts 41 and 42 of turnbuckles 43, two turnbuckles being used as diametrically opposite sides of the build ing, to thus form a continuous cable around the perimeter of the building. The rafters may now be fastened tightly to the compression ring.

The turnbuckles are now tightened to shorten and apply tension to the cable. Shortening or lengthening the tensioned cable will increase or decrease the slope of the rafters simultaneously, and, because of the cable connection between the rafters and wall sections, will move the upper ends of the wall sections inwardly or outwardly. The turnbuckles are adjusted so that the wall sections are plumbed vertically. At this time, the compression ring will have been shifted laterally, if needed, so that it is centered relative to the building. During this wall plumbing operation the temporary wall braces 36 may be removed if they interfere with the plumbing. After plumbing, the wall sections are secured tightly to the floor.

Upright bearing posts 13 are now installed between the ends of the wall sections to extend from the floor up to supporting engagement with the rafters. Wedgeshaped filler strips 44 are inserted between the ends of the wall sections and posts 13 and nails are driven through the end studs and filler strips into the posts to fasten the posts in place. With the rafter structure being now supported by the posts 13, the temporary rafter braces 38 may now be removed.

In some instances where extremely severe snow loads are to be expected, pole 37 may be left in place for support purposes, if desired. Normally, however, the pole is removed so that the interior of the building is unobstructed thereby.

The purlins 45 and intermediate rafters 46 are then installed, and the building is roofed and finished in a structive forces applied thereto, either during construction or after the building is completed. In previous construction wherein a perimeter wall has been erected and plumbed and a reinforcing cable put around the building the cable has been tensioned before the rafters have been put in place, with the cable tension being at least sufficient to provide sufficient resistance against wall spreading under the combined weight of the later added roof and the expected snow load thereon. Since the amount of cable tension is difficult to determine without special equipment, the cable is usually tensioned beyond that which will actually be needed. Such cable tension puts a high compressive end-to-end force on the wall sections, particularly before any rafters are installed, and may crush or otherwise damage the wall sections. In the present invention, the cable is not tensioned until after the rafter assembly has been put in place, and thus there is no compressive force exerted on the wall sections by the cable before that time. When the cable is tensioned the walls will be plumbed. Over-tensioning is avoided because if the cable were continued to be tensioned after the walls were plumb the wall sections would tilt inwardly and lose their plumb. Thus, as soon as the walls are plumbed, cable tensioning is stopped. The length of the cable between adjacent rafters is a function of the pitch of the rafters. If such length for the desired roof pitch of the plumbed building is not less than the length of the wall section, then there will be no end-to-end compressive force exerted on the wall section.

The weight of the rafters and later roof bears down on the support posts between the ends of the wall sections and thus little downward force is exerted on the wall sections by the roof.

The only significant forces on the wall sections will be from racking due to high winds or earthquakes.

Another important aspect of the present invention is that there are no connections of the rafters to each other or to the perimeter wall which are subject to failure under shear. Although screws are used to secure the rafters to the compression ring, these screws are simply hold-down devices and are not subject to shear failure. The real force present in the compressive force between the upper ends of the rafters and the upper flange of the compression ring.

The connection between the lower ends of the rafters and the perimeter wall is by means of the perimeter cable which passes through the rafters and through the 'end studs of the wall sections. Thus, there is no fastening between the rafters and wall sections which can pull out of one or the other when a shear force is applied.

This is quite important when building are constructed in localities subject to earthquakes. With conventional 'fastening of the roof to the walls, the high lateral shaking force imposed on the building during an earthquake will often tear the fastening loose, allowing the roof to tear and slide off the walls. With the present construction the cable would have to be torn laterally through the end studs or rafters before any separation of the roof and wall would occur.

The cable connection provides a pivotal connection between the rafters and wall sections which allows the slope of the rafters and wall sections to vary during the plumbing operation without imposing a weakening strain on the connection.

After the building is constructed, snow loads on the roof will cause some flexure of the rafters along the length thereof. If the rafters were rigidly connected to the wall, such flexure would exert an undesired strain on the connection. However, because of the pivotal movement allowed by the present cable connection, rafter flexure from roof loads will not adversely affect the connection.

Having thus described my invention, I claim:

1. A method of erecting a building comprising:

a. forming a perimeter wall by putting up a plurality of rectangular wall sections in end-to-end relation but spaced-apart relation, said wall sections being secured against movement of their lower ends and being temporarily supported in roughly plumbed position,

b. supporting a compression ring approximately centrally of and above said perimeter wall,

c. securing the upper end of a rafter to said compression ring,

d. temporarily supporting the lower end of said rafter between the upper ends of a pair of adjacent wall sections,

e. repeating steps (c) and (d) so that there is a rafter between each pair of adjacent wall sections,

f. passing a perimeter cable through the upper end of each wall section and through the lower end of each rafter,

g. applying a tension force to the ends of said cable,

h. adjusting the amount of tension force to plumb the rectangular wall sections.

2. A method as set forth in claim 1 wherein the temporary supports for said wall sections are removed between steps (g) and (h).

3. A method as set forth in claim 1 and further including the steps of:

i. positioning an upright post between each pair of adjacent wall sections and extending upwardly into supporting engagement with the rafter thereat,

j. fastening said upright posts to said wall sections after step (h). 

1. A method of erecting a building comprising: a. forming a perimeter wall by putting up a plurality of rectangular wall sections in end-to-end relation but spacedapart relation, said wall sections being secured against movement of their lower ends and being temporarily supported in roughly plumbed position, b. supporting a compression ring approximately centrally of and above said perimeter wall, c. securing the upper end of a rafter to said compression ring, d. temporarily supporting the lower end of said rafter between the upper ends of a pair of adjacent wall sections, e. repeating steps (c) and (d) so that there is a rafter between each pair of adjacent wall sections, f. passing a perimeter cable through the upper end of each wall section and through the lower end of each rafter, g. applying a tension force to the ends of said cable, h. adjusting the amount of tension force to plumb the rectangular wall sections.
 2. A method as set forth in claim 1 wherein the temporary supports for said wall sections are removed Between steps (g) and (h).
 3. A method as set forth in claim 1 and further including the steps of: i. positioning an upright post between each pair of adjacent wall sections and extending upwardly into supporting engagement with the rafter thereat, j. fastening said upright posts to said wall sections after step (h). 